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When to Plant Lemon Balm in Mendocino County, CA

Mendocino County, California Zone 9b May

What to do in May

A quick May briefing for Mendocino County, California gardeners — what's urgent, what's next, and what can wait.

Avg. last frost March 23
Avg. first frost November 9
Soil temp (4") 71°F
Watering Critical
Pest pressure High
Daylight 14.2 hrs
Looking ahead to June
  • First harvests: lemon balm

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Lemon balm is a vigorous perennial herb with bright green, lemon-scented leaves. It makes a refreshing tea and is easy to grow but can spread aggressively.

Mendocino County, California is in USDA Zone 9b. The average last spring frost is March 23 and the first fall frost is November 9, giving you a growing season of approximately 231 days.

At an elevation of 180 feet, Mendocino County receives approximately 24 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 87°F, providing good warmth for Lemon Balm during the growing season. Sandy soil warms quickly in spring — great for early planting — but Lemon Balm will need more frequent watering and organic matter to retain nutrients.

Mendocino County, CA (Zone 9b) Long season
231 days
Last Spring Frost March 23
231 growing days
First Fall Frost November 9

Mendocino County Soil Profile

Soil Type

Sandy Loam

Soil pH

6.1-7.2

Drainage

Well Drained

Monthly Watering Guide for Lemon Balm

Lemon Balm needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Lemon Balm Needs Rainfall You Supplement Action
Jan 5.2" 0" ❄️ Dormant
Feb 4.6" 0" ❄️ Dormant
Mar 4.3" 3.7" 0.6" 💧 Light watering
Apr 4.3" 1.9" 2.4" 🚿 Regular watering
May 4.3" 0.6" 3.7" 🚿 Regular watering
Jun 4.3" 0.2" 4.1" 🚿 Regular watering
Jul 4.3" 0" 4.3" 🚿 Regular watering
Aug 4.3" 0" 4.3" 🚿 Regular watering
Sep 4.3" 0.2" 4.1" 🚿 Regular watering
Oct 4.3" 1" 3.3" 🚿 Regular watering
Nov 4.3" 2.6" 1.7" 💧 Light watering
Dec 3.9" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Mendocino County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Lemon Balm Planting Timeline — Mendocino County, CA

Lemon Balm Planting Calendar

Activity When Date Range
Transplant Outdoors March 30 Mar 30 – Apr 13
Harvest June 1 Jun 1 – Jul 20

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March Transplant Outdoors
April Transplant Outdoors
May
June Harvest
July Harvest
August
September
October
November
December

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

Moderate — regular watering

📅 Days to Maturity

60–70 days

🧪 Soil pH

Needs 5.5–7.5 · Your soil: N/A

🗺️ USDA Zone

Zone 9b

📆 Growing Season

231 days in Mendocino County

Growing Tips for Mendocino County

Start from seed, cuttings, or divisions. Contain in pots or use barriers to prevent spreading. Harvest frequently to keep plants bushy and prevent flowering.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Lemon Balm in Mendocino County, CA?

Mendocino County is in Zone 9b with an average last frost of March 23. Plan your Lemon Balm planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mendocino County, CA?

Mendocino County, California is in USDA Hardiness Zone 9b. The average last spring frost is March 23 and first fall frost is November 9.

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Your Mendocino County Garden Planner — Free

A 24-page printable planner built for Mendocino County (Zone 9b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Mendocino County, CA. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.